Vacuum toilet systems are widely used in various applications such as trains and marine vessels, in place of standard, gravity operated toilets found in most homes. Instead of using gravity drainage piping, the toilet discharge is connected to a vacuum source which pulls waste material through a discharge pipe to a collection tank. A waste-receiving bowl is attached to the discharge pipe, and a discharge valve disposed in the discharge pipe controls when a vacuum is present in the bowl. One or more nozzles for dispensing rinse fluid are typically located around a rim of the waste-receiving bowl.
To provide a more complete rinse, it is desirable to use fluid that is under pressure. Pressurized water is not always available on trains or marine applications, but pressurized air generally is. Accordingly, one type of device is known which uses pressurized air to provide pressurized rinse water. This device has a diaphragm disposed inside a reservoir and movable between first and second positions. A spring pushes the diaphragm to the first position which allows a large volume of water to enter the reservoir. Pressurized air is then used to overcome the force of the spring and push the diaphragm to the second, compressed position. The diaphragm in the second position pressurizes the water in the chamber to a pressure equal to that of the incoming air. The pressurized water flows out of the reservoir to rinse the bowl. A similar device uses vacuum instead of the return spring to move the diaphragm to the first position. The water pressurizers having diaphragms are overly costly and difficult to assemble.
Another type of water pressurizer uses a controller and electronically operated solenoid valves. A solenoid valve is used to control communication between the source of pressurized air and the reservoir so that, when the valve is opened, the fluid in the reservoir is pressurized. Another solenoid valve is used to control discharge of the pressurized fluid from the reservoir. Additional solenoid valves may be used to provide other functions such as controlling when unpressurized water is delivered to the reservoir. These water pressurizing systems require a power source to operate and requires components which are overly expensive.